Repairing a Full Length Back Crack with a Go-Bar Deck:
This Guild Jumbo acoustic had one of the most extensive cracks I’ve ever seen. It ran the full length of its back. The cause of this crack was MAJOR dehydration – and years of it. The crack was not only wide open, but the wood had also warped substantially on either side of it.
I unfortunately did not take a picture of the original damage. I was skeptical if the instruments could be fixed. It required almost a month of prep to reshape the wood for the repair and i wasn’t convinced it could actually be done (and start to blog it) a month in.
Prep work went like this:
1. Intentionally over-hydrate the instrument for 3 weeks.
2. Wet the inside of the guitar along the crack with hot water.
3. Install 2 spreader clamps from the crack area to a a top brace.
4. Clamp the instrument in the Go-Bar deck (See Pic Below) and let sit for 24 hours.
I did this 6 times before he guitar was ready to glue!
Oh yeah: What’s a Go-Bar Deck?
Go Bar decks are a traditional, and common, clamping system for building acoustic guitars. They come in handy for repairs sometimes too. Originally the bars were made of wood, mine are plexiglass (like tent poles) with rubber ends. Slightly bent they pressure between the bottom & top of the deck.
So, once the wood was made to lie flat and crack closed up I repeated the same process, minus wetting the wood with hot water, with Hide Glue. Same pic as above.
Next came the braces.
A better view. Go bars sometimes pop off braces. The plexiglass on either side is to protect the top if that happens ( it did twice).
Please note: The guitar is sitting on top of carpet on top of a radius dish (the same radius as the side facing it). This was essential to the process.
Because of the 3 braces crossing the crack, reinforcement wasn’t a big issue. I only needed to install one cleat near the bottom. Made of mahogany (same as the back), about 1″ x 3/8″ & 1/16″ thick, and glued cross grain, the cleat helps keep the crack from reopening. It is double stick taped to a magnet, which is used to locate it and clamp it in place.
Low tack masking tape was used protect the top and locate proper cleat placement.
3 magnets (kept from tuning in on themselves with heavy duty masking tape) give clamp pressure to the cleat.
You can see the closed crack above and below the tape, not perfect, but far better.
Thanks for reading!